Aide memoire

My 2-element quad's feed broke today, just as I was about to do some other work in the 32 degree heat.  It has always had a very cheap, aluminium outer conductor, 75Ohm 1/4 wave stub, and has now reached 6 years of age.

The 6m quad, battered by weather for 6 years, rises again!

 
Turning the quad towards North America, the 75Ohm coax broke at the feed point again.  The aluminium outer very rapidly corrodes to powder, especially near the sea as we are.

I decided to finally replace the stub, though I have had recent problems determining the proper electrical length using an antenna analyser.  It's worked perfectly for other bands, but for some reason, doesn't on 6m.

So I decided to cut some spare, all-copper low loss 75Ohm coax to the same length as the old cheap coax.  On this occasion, I was lucky, as it returned a near-perfect 50Ohm transformation - actually just over 48Ohms - the SWR being about 1.03:1 at 50.00MHz (the antenna proves to be lightly and inconsequentially too long). It remains well below 1.3:1 way out to above 50.4MHz.

Pretty pleased with that result!  For the record, the correct 75Ohm stub length is 115cm, with the coax characteristics apparently not being that important between types.  The length is also not super-critical, at least for this quad type antenna.

I'm having a rest - by losing sleep!

Midsummer this year is proving to be incredibly warm and dry.

It's also a bit dry on the radio, as house maintenance and other matters have taken over.

This is also the time of year I lose tens of hours of sleep to researching and simply observing noctilcuent clouds.

If you happen to be in the latitude range of about 50-60 N, you might want to go keep an eye on the NW to NE late evening and very early morning sky.  You could spot noctilucent clouds, or what the newspapers called 'space clouds' after I broadcast about them on BBC Radio in 2010/11.

If you like this sort of thing, you can come along to my Facebook 'Space_Clouds' page and join in!

Interesting site - LED RFI

This is worth a look.  Sadly, it's a disease of the ham culture not to publish details of the products that do not produce RFI. 

http://www.ledbenchmark.com/faq/LED-interference-issues.html

HF/VHF Bandplans - Thanks EURAO!

I joined EURAO last year because I have consistently found the RSGB does not reflect my view of modern amateur radio at all.  The ARRL was better, but it is firmly US-centric, for obvious reasons.

EURAO is slowly gaining in influence, though it remains an upstart in the highly machoistic, male-dominated radio establishment.  Contact with IARU Region 1 representatives has often looked like a car crash.

Doing what it can to change the radio establishment.

What I do like about EURAO is that it is not pinned down by some old-fashioned ideas of 'how things used to be'.  It looks forward, rather than backwards.

So here's EURAO's latest attempt to make itself relevant.  It's just a simple bandplan/frequency guide, but it's very useful.

The guide might even teach all those RTTY and FT8 operators, who often stamp on other modes, where they should not operate!

Receiving Weather Satellites!

Idle browsing on the internet the other day led me to have a go at receiving NOAA weather satellites this afternoon.

I used my normal 2m slimjim antenna (not resonant at 137MHz, but near enough for such a strong signal), a 2m FM rig, and a USB sound dongle (now selling for less than £1 online) to feed the computer.

Using WXtoIMG freeware/optional payware, I found it was very easy to receive a strong, stable signal without any real need for Doppler adjustments during the passes.

Here's an example I received from NOAA 19 this tea time.  It's lovely in Iceland!

CQD

One thing I love to do on rare occasions when I can, is collect radio memorabilia.

Not that I'm a big collector.  At the moment, I only have two original, very large ceramic 'egg' insulators from a local Marconi transmitting station, which sent the first direct (non-relay) signal from the UK to Australia in 1918 (centenary this year).

So I was quite pleased to find a good quality 'CQD' medal from 1909 for sale for quite a good price of £450 recently.

Obviously, in 1909, commercial radio was very new, and this medal commemorates the successful use of the first major distress signal to be broadcast at sea, saving over 1700 lives.

The Imperial War Museum records give the following details about a similar medal.  The images are of the specific medal I am acquiring:

This medal takes its name from the CQD emergency radio signal - predecessor of SOS - sent out by the stricken White Star steamship 'Republic' after it collided with the Italian steamer Florida on 21 January 1909. 

The liner 'Baltic' responded to the call. The 'Republic' was the more severely damaged vessel, but all her passengers were transferred first to Florida and then to the Baltic, before the Republic sank. 

The saloon passengers of the 'Baltic' and the 'Republic' subscribed to a fund to provide medals to the crews of all three ships involved in saving over 1700 lives. 

Four silver-gilt examples were presented to the three captains, and to Jack Binns, the Marconi operator on the 'Republic' who sent the CQD radio signal. Silver medals were presented to the officers, and bronze to the crew. 

This medal, in silver, was to Robert Jones, who was a Marconi Radio Operator involved, probably an Assistant on the 'Baltic', which had two operators (for continuous watch coverage). This requires further research. 

Jack Binns was made a national hero for sticking to his radio post until the last minute - it could well have been Robert Jones that he was, in part, communicating with (as well as several land-based stations). 

Robert Jones (April 1889 - 1 March 1951) served as a wireless operator at sea for the Marconi company until 1919, when he took a shore-based position as a radio engineer, eventually to retire just prior to the Second World War. 

The 'family story' is that he was sunk on three ships during the First World War, and that by the time of the Armistice his nerves (and lungs) were 'ruined'. The Family have notes to indicate he had served at some time on four vessels that were lost in the war, although it is not certain that he was aboard all of them when there were lost (needs research): - 'Hesperian' (liner, sunk 4 Sept 1915) - 'Cymric' (liner, sunk 8 April 1916) - 'Appam' (captured 15 Jan 1916 by surface raider Moewe - with a prize crew of 23 steamed to US, where Germans attempted to have the British crew (160) and passengers (170) interned; notable legal dispute at the time - Jones perhaps temporarily a POW in USA) - 'Kittiwake' (sunk 9 April 1917 - seems very small compared to these other vessels - only 1866 tons?)

Magnetic loop - careful what you believe!

A long spell of warm, dry and calm weather has been blessing north Wales recently. Prime time for magnetic loop testing where the tuning capacitor isn't weather proof!

Like all good antennas, it doesn't have to look good.  It just has to work!  Note the non-primary loop feed mechanism.

I've had very good results with the magloop in earlier tests, where the WSPR outcome matched many full-sized wires.

I decided to have another go at 14MHz with my 1.2m per side, square, 28mm copper pipe loop.

Here is the pattern of the vertically polarised radiation, according to MMANA-GAL:

Vertical radiation pattern, magnetic loop, looking from above.

There is also a horizontal radiation component, 3dB weaker than the vertical component:

Horizontally polarised radiation, magnetic loop from above.

 
For all of you who slavishly repeat the primary 'Faraday' loop feed mechanism, you may well wish to abandon it.  The very few serious magnetic loop researchers I know of use a pseudo-gamma match.  This is best explained with a simple schematic, where the solid blue depicts the loop, and yellow the feeding. 

This is simply a triangle of wire from one side of a 4:1 balun, soldered about 3/4 the way up one side (best position found by experiment).  The other side of the balun is just connected in the middle of the lower tube.  The capacitor (not shown) sits at the top.  This 'pseudo-gamma' matching system is a combination of direct and induced feed.

For this week's run, the matching omitted the hypotenuse of the triangle, using just an 'L'-shaped feed running close to the the loop.

Back to the WSPR run.

The matching was 1.09:1 at the WSPR frequency, and the tuning capacitor a 25-165pF wide-spaced air butterfly.  All data is for 36h of spots.

I compared with G8LIK, who runs an efficient, large horizontal wire loop from a good, relatively open site. Because WSPR inevitably means comparisons of other people's antennas, it's important to note that none of this blog aims to be mindlessly critical of others' antennas.  Indeed, I am very grateful to all comparison stations, all of which have been carefully chosen for the quality of their antenna installations and long-term, proven WSPR efficiency.

And for those who may ask why I am not comparing with, say, a vertical antenna, the reason is, frustratingly, that it is very hard to find a good quality antenna in a good environment and that is operating on WSPR for more than a quick test of an hour or two!

SNR across all distances.

I've managed to crop the reported comparison, but my magloop was 3dB weaker across all spots as compared to G8LIK's full loop.  In itself, that's a very good result for such a small antenna that is also completely outside any town planning restrictions in the vast majority of installation situations.

Now, I became a little disappointed when I looked at how my magnetic loop compared with reports from beyond 2400km - what you might call 'DX' distances:

SNR beyond 2400km.

I am now 13dB below the full wire loop!  I can't remember things being that bad in any other test.

Something is wrong!  Let's look at the graph of distances achieved over 36h:

No doubt at all that my magnetic loop matches the full wire loop during the day, and considerably outperforms the wire loop during the evening.

Looking at the spot reports, it becomes clear that I was only 13dB weaker to one station - EA8BFK - who is in the sharp null of my NW-SE aligned loop, and obscured by my house:

As I've reported previously, when you run WSPR tests and use data analysis tools, you have to consider all the analyses, not just some of them.

I could have concluded my magnetic loop was useless for DX, unless I looked at the distances achieved and, more clearly, the map of all spots for both stations.  Rather obviously, my small magnetic loop reaches far into north America, whilst the full horizontal wire completely fails to get across the Atlantic. 

All spots, 36h of data.

For good measure, I include VK7JJ's web-based analysis of my spots, which reports around 36,000km per Watt equivalent SNR for my magloop, compared with just 14,000km/Watt for G8LIK.

How about a comparison with a half-sized G5RV firing E-W (confirmed with the operator, G4WIM, 11/6/2018), to address the hardcore naysayers?  This plot is for a week, with a gap where I was charging the USB battery.

On long-haul DX, beyond 5000km, the half-sized G5RV is 3dB stronger than my magnetic loop.  That's still a very good result for the loop:

SNR comparison with half-sized G5RV beyond 5000km.

In terms of spot 'quality', G4WIM's half sized G5RV comes in at around 41,000km per Watt equivalent, some 4000km per Watt above my magnetic loop:

I'm not sure why I keep repeating this experiment, other than to keep providing data to those who claim magnetic loops are 'just dummy loads'.  WSPR has no opinions or human bias.  It just reports the truth.  Clearly, magnetic loops work.  It's just a shame that trying to make a weatherpoof, micro-adjustable tuning capacitor is a bit tough, at least for people like me who are not very good at electronics!

Useful find of the day.

The APRS web site for WSPR reports hasn't been working today.  Very annoying, as I wanted to run my magnetic loop at 20m.

As a result, I came across this very useful site, which provides not only spot reports, but lots of analysis, too.

Windows 10 Updates - WARNING!

My Windows 10 laptop decided to mandatory self update this afternoon.

As predicted, this immediately led to disaster with the amateur radio equipment.  My external audio interface, which has been working perfectly fine until the update, is now unable to be opened as an input by any digimode software!

The update also led to my computer being very slow, despite my declining all the 'new' fancy  consumerist options people like Microsoft imagine I want, but in fact don't.

Windows does at least offer the option, under settings, to roll back to the earlier version, although it's unclear (to me at least) whether this roll-back is permitted forever. 

Most of the changes in the update had to do with voice recognition (Cortana), and so I presume there is some conflict caused by audio settings somewhere in the depths of Windows.

Unfortunately for Microsoft, this kind of mandatory taking control of my computer and causing it to malfunction is yet another reason to abandon Windows altogether.  I already have a lovely Raspberry Pi running Linux with absolutely none of the idiotic things that Microsoft insists upon, and at a fraction of the cost of a Windows machine.

So, if you see that message asking you to update, do everything you can to avoid updating.  In fact, do everything you can to avoid Microsoft Windows, whose days really must be numbered if they continue on this American-centric view of the world and its control.